A wiki? Unless you're heavily into the Internet, chances are you're wondering what the heck that is.

The wiki concept was created by Ward Cunningham, who joined Microsoft last month after working as a consultant to the company. Cunningham set out in 1995 to create a unique online site for people involved in technical aspects of a type of software development known as object-oriented programming.

A wiki is a computer program that lets people around the world collaborate to create and update Web pages. The resulting collections of pages are also known as wikis. But there's more to it than that. Anyone who reads a wiki -- yes, anyone -- can also easily make changes, corrections and additions, create whole new pages, and even correct the way the wiki is organized.

"It took a while for this to catch on because it sounded so unusual, but I've now got 25,000 pages about programming up on that site," Cunningham said last week.

But Cunningham himself wrote only about 100 or 200 of those pages. The rest were contributed and shaped by others who chose to take part in the process. That shows the unique power of a wiki as a repository of human knowledge and ideas. The wiki derives its name from wiki wiki, the Hawaiian phrase meaning quick -- reflecting the pace at which wiki pages can be created and updated.

The wiki concept has become "a study in what's now called social software -- anything where the real behavior is not possible if there's only one person using it," Cunningham said. With a wiki, "I write the seed of the idea and I come back in a week and see how the idea has grown."

The concept has also caught on with many others, but Cunningham's original wiki remains the largest devoted to a single subject. The largest wiki on multiple subjects is the English version of wikipedia, an online encyclopedia created by volunteers who contribute information based on their expertise or knowledge.

Wikipedia was created in January 2001 by people who had previously tried a different approach -- with more complicated tools and a more rigorous process of pre-publication review -- to create an online encyclopedia called Nupedia. They saw what Cunningham was doing, and decided to give it a try, said Wikipedia founder Jimmy Wales.

"To me, it's just one of those flashes of genius, the spark of the idea that he had," Wales said. "It's so powerful. But it really is simple. Any idiot could think, 'Oh, let anybody edit the site ...' but none of the rest of us idiots did think of it."

Wales acknowledged that the idea takes some getting used to. "It sounds insane, right? You have a Web site and anyone can edit it? Isn't that a disaster? But it works amazingly well."

What happens, though, when people contribute something incorrect, or remove something the broader community considers valuable? The key is to have enough participation that someone, somewhere in the world, quickly sees what has happened and corrects it. Cunningham experienced that with the first wiki.

"As it slowly became more and more known, the community of protectors grew," Cunningham said. "A lot of people will get on there and say, 'Can I really change this?' and they'll write 'Can I change this?' right on the page. Somebody within seconds will come back and they'll erase it."

For all this talk of wikis, however, Cunningham's work at Microsoft has more to do with his experience in object-oriented programming, through which programs are built based on distinct pieces of reusable code. Cunningham also was a co-developer of a practice called extreme programming, a set of practices that let developers use object-oriented programming to quickly adapt to the changing needs of businesses.

Cunningham, 54, grew up in Indiana and studied electrical engineering as an undergraduate and went into computer science as a graduate student at Purdue University. In the late 1970s, he came to Oregon to work in the research lab at Tektronix. He was introduced to object-oriented programming there through a collaboration with the Xerox Palo Alto Research Center.

He ultimately became an independent consultant, focusing on areas of computer science including something known as "patterns," which identify solutions to recurring problems in object-oriented programming. That is the focus of his original wiki, the Portland Pattern Repository.

Cunningham is an architect in Microsoft's Prescriptive Architecture Guidance group, which produces patterns and practices for developers using Microsoft's .Net development platform. The position lets him continue and expand the same type of work he was doing in his position as an independent consultant.

Although wikis aren't the focus of his new job, Cunningham continues to take part in them. After accepting the Microsoft position, for example, he started a wiki page called Tips For Ward at Microsoft, on which a wide range of people, including some Microsoft employees, have offered him suggestions for how to survive and thrive at the company.